`this` Pointer

Inside a non-static member function, this points to the object that called the function.

Simple idea:

this = address of the current object

Example

#include <iostream>

class Counter {
private:
    int value = 0;

public:
    void increment() {
        this->value++;
    }

    int getValue() const {
        return this->value;
    }
};

int main() {
    Counter counter;
    counter.increment();
    std::cout << counter.getValue() << '\n';
}

You usually do not need to write this-> unless it improves clarity or solves a name conflict.

Resolving Name Shadowing

Sometimes a parameter has the same name as a data member.

class Employee {
private:
    int id = 0;

public:
    void setId(int id) {
        this->id = id;
    }
};

Without this->, id = id; would assign the parameter to itself.

Returning *this

this is a pointer.

*this means the current object.

Returning *this allows method chaining.

#include <iostream>

class Box {
private:
    int length = 0;
    int width = 0;

public:
    Box& setLength(int value) {
        length = value;
        return *this;
    }

    Box& setWidth(int value) {
        width = value;
        return *this;
    }

    void display() const {
        std::cout << length << " x " << width << '\n';
    }
};

int main() {
    Box box;
    box.setLength(10).setWidth(5);
    box.display();
}

Important Guides

• Only non-static member functions have this.
• Friend functions do not have this because they are not member functions.
• You do not declare this; the compiler provides it.
• In a normal member function, this behaves like a constant pointer to the current object.

Viva Answer

this is an implicit pointer available inside non-static member functions. It points to the current object. It is useful for resolving name conflicts and returning *this for method chaining. Friend functions do not have this because they are not members.

Quick Check

• What does this point to?
• Does a friend function have this?
• Why use this->id = id?
• What does returning *this allow?